1. Field of the Invention
The present invention relates to a technique in which presence or absence of a traffic jam is determined in an on-vehicle terminal apparatus.
2. Description of the Related Art
Consideration of road-to-vehicle communications is underway to prevent encounter head traffic accidents at intersections. In the road-to-vehicle communication, information on the situations of an intersection are communicated between a road-side device and on-vehicle equipment. In the road-to-vehicle communication, it becomes necessary to install the road-side devices, which requires a large effort and high cost. On the other hand, a system is to be established in which a traffic jam is predicted by vehicle-to-vehicle communication, such as ITS (Intelligent Transport Systems). In the vehicle-to-vehicle communication, i.e., in a mode in which information are communicated between the on-vehicle equipments, it is not necessary to install the road-side devices.
In Japanese Patent Application Publication No. 2009-188527, it is disclosed that, in a vehicle-to-vehicle communication apparatus, vehicles that exist around the most nearby intersection and travel in the same direction as those of a driver's vehicle are defined as the same vehicle group as the driver's vehicle, and the transmission period in a representative vehicle of the same vehicle group is made short and the transmission period in the vehicles other than the representative vehicle is made long. Thereby, an increase in the communication traffic between the vehicles of the same vehicle group can be suppressed.